The need to understand complex social, economic, and environmental phenomena has driven statistical research to develop methodologies that can synthesize data without losing too much information. Composite indices allow us to reduce the dimensions of a multidimensional phenomenon in order to represent its complex reality.

In recent years, Istat has adopted these techniques to measure the fragility, hardship, and poverty of even very small areas. This lesson aims to present the most widely used methodologies and composite indices that attract the attention of politicians and media.